Monday's face-to-face meeting and handshake between Robert Mugabe and Morgan Tsvangirai in Harare to sign a "preliminary agreement laying out terms for negotiations to wrest their land out of political chaos" (as the New York Times described it) has to be judged for what it is. This is a historic moment and even some us used to the double-dealing of Mugabe's regime and that of Thabo Mbeki, the South African president and mediator between the parties, should celebrate it for that reason. This is the first time the two men met since the late 1990s (in 1999, to be exact), when Mugabe was forced to meet with Tsvangirai, then head of the country's trade union movement.

The meeting also represents somewhat of a climbdown for Mugabe, and his junta, who had vowed to govern until God removed him (shades of Rhodesian leader Ian Smith's "1,000 years") and whose only response to Tsvangirai and his supporters since they first defeated Mugabe and Zanu-PF in a referendum in 2000 has been violence, murder and intimidation and outright electoral fraud.

Reports of the meeting describe Mugabe as striking more measured tones than his until now strident and incendiary rhetoric. What happens ahead is contingent on a number of factors: there are the security forces (the army and police), which both act as the private army of the ruling Zanu-PF party, state violence (the agreement creates the pretence that both the state/Zanu-PF, on the one hand, and the opposition MDC, on the other, are equally culpable), and new ethical rules about the governance of state organs (reforming electoral machinery for one) and equal access to public media (it is interesting that the government put the issue of "external radio stations on the agenda" an obvious reference to the British-based SW Radio Africa). Finally, there is the question of Mr Mugabe's legitimacy.

The last has consequences for how power will be distributed between the parties in any transitional government. After Tsvangirai won a March 29 presidential election, the Zimbabwean government held back the result for a month, and said the opposition had not won by a large enough margin and called a new election. Having terrorised the opposition supporters to the point where Morgan Tsvangirai felt compelled to withdraw at the last minute, Robert Mugabe went ahead, ran again himself and declared himself president for another six-year term. As most news organisations reported, yesterday's agreement, apart from imploring the parties (including a Zanu-PF-leaning MDC faction sit down and talk) does not address the central issue of Mr Mugabe's future or goes into the details of any power-sharing arrangement.

So, what about the third major personality in this drama: Thabo Mbeki? Of course, Mbeki (and what's left of his supporters and defenders) will claim that his policy of "quiet diplomacy" has worked. Mbeki can definitely take credit for yesterday's meeting, but that comes after eight years of despotism, hundreds of deaths, thousands homeless, and the devastation of the Zimbabwean economy. In the process, Mbeki has also left Mugabe emboldened (let us remember that Mugabe still holds the upper hand: he is in office, controls what's left of the state, has the loyalty of the army, the police, prison services, electoral commission and means of propaganda). And, as reports from South Africa indicate, the Mbeki policy has been privately opposed to granting the MDC a seat at the table, favoring a Zanu-PF-leaning opposition candidate, the former finance minister Simba Makoni.

Ultimately, general international pressure has been the telling factor. It is significant that this meeting happened after Mbeki was forced to include African Union and United Nations representatives on his mediating team. In the end, Mbeki does deserve some credit as this was probably the only process Mugabe would engage with. But it also may be the case that Mbeki's own influence will wane now.